U.S. President Donald Trump boards Air Force One to depart for Vietnam from Beijing Airport in Beijing, China on November 10, 2017. (Photo by Jonathan Ernst/Reuters)

Indian students smear coloured powder during an event to celebrate the Hindu festival of Holi in Kolkata on February 26, 2018. Holi, the popular Hindu spring festival of colours is observed in India at the end of the winter season on the last full moon of the lunar month, and will be celebrated on March 1 this year. (Photo by Dibyangshu Sarkar/AFP Photo)

Beda Haemmerli drives his 1936 Ford Indy race car (front) through a steep turn during the Indianapolis in Oerlikon race demonstration at the Offene Rennbahn cycling track in Zurich's Oerlikon suburb, Switzerland July 24, 2018. (Photo by Arnd Wiegmann/Reuters)

A woman touches a robot at the 2018 World Robot Conference in Beijing on August 15, 2018. The conference will be held from 15 to 19 August and will include a conference on robotics, an exhibition and a robot competition with the participation of robotics enterprises to showcase their robot products. (Photo by Wang Zhao/AFP Photo)

A Maasai boy bites a bull's heart during an initiation into an age group ceremony near the town of Bisil, Kajiado county, Kenya, August 23, 2018. Thousands of Kenyan boys had a blessing of milk and beer sprayed on them as part of a rare Maasai ethnic community initiation ceremony to mark their passing into early manhood. (Photo by Baz Ratner/Reuters)

In this photograph taken on April 28, 2018, Afghan children work at a coal yard on the outskirts of Jalalabad, Afghanistan. (Photo by Noorullah Shirzada/AFP Photo)

Katie Boulter celebrates winning her match against Kazakhstan for Great Britain who went on to win the Federation Cup Tennis World Group II play-off at Copper Box Arena in London, England on April 21, 2019. (Photo by Shaun Brooks/Action Plus via Getty Images)

A Darjeeling Himalayan Railway steam train, which runs on a 2 foot gauge railway and is a UNESCO World Heritage Site, passes by a market in Ghum, India, June 27, 2019. (Photo by Ranita Roy/Reuters)